It happens every year: reigning division champions are brought down by upstart challengers to the throne.

Well, with the draft done and most free agents signed, let's attempt to get ahead of the curve by assessing the most vulnerable division winners from 2015. Below, listed in reverse order (that is, from least vulnerable to most) is my look at the teams in danger of losing their grip on their division in 2016, along with the club best positioned to push each leader.

8) Washington Redskins

This division has crowned a new winner every year since 2005, with Washington finishing last six times in that span. Yet, I like the Redskins to repeat in 2016, just because they've put together a pretty good roster and should be playing with plenty of confidence. Kirk Cousins had a great 2015 (69.8 percent completion rate, 29 touchdowns, 11 picks, 101.6 passer rating) and should solidify his status as a viable NFL quarterback, especially when you consider the incentive in front of him as a franchise-tagged player. The Ryan Kerrigan-led defense will get a boost from the addition of Josh Norman and the return of Junior Galette (who missed 2015 with a torn Achilles tendon), while rookie receiver Josh Doctson will only augment a pass-catching crew that includes DeSean Jackson, Pierre Garcon and matchup nightmare Jordan Reed at tight end.

7) Arizona Cardinals

Arizona made two big moves to solidify its hold on the division: trading for veteran pass rusher Chandler Jones and rolling the dice on Robert Nkemdiche in the draft. Pass rush was one of the things the Cards needed last season after tying for 20th in the NFL with 36 sacks, and Jones (12.5 sacks in 2015) addresses that. Nkemdiche, meanwhile, brings some youth to the line of a defense that is otherwise set at linebacker and in the secondary. The Cardinals are stacked with offensive weapons, including all-hands candidate Larry Fitzgerald and up-and-coming young running back David Johnson. Carson Palmer's age (36) worries you a bit, but he should have another good season in 2016 after posting career highs in passer rating (104.6), touchdowns (35) and yards (4,671).

The Seahawks always loom with their imposing combination of outstanding quarterback play, dominant defense and the leadership of Pete Carroll. But I think Arizona is the more complete team, given Seattle's question marks on the offensive line, in the receiving corps and at running back. Thus, the Cards will repeat as division champions for the first time since the Kurt Warner era drew to a close.

6) Carolina Panthers

The Panthers' biggest losses were cornerback Josh Norman and punter Brad Nortman. Otherwise, Carolina returns most of the key pieces of a squad that upended expectations in reaching Super Bowl 50 without injured No. 1 receiver Kelvin Benjamin -- who will really help the passing game in his return to action. In the draft, the Panthers added Vernon Butler, who can help buttress an already dominant front seven, and a group of defensive backs who should help make up for Norman's departure. Reigning MVP Cam Newton takes a step forward every year, and I expect that to continue in 2016.

The Falcons significantly boosted their roster, upgrading at center (Alex Mack) and at No. 2 receiver (Mohamed Sanu). Rookie safety Keanu Neal is like Kam Chancellor with speed. Coach Dan Quinn is a bit of an undervalued gem. Yes, he presided over a six-game losing streak in the middle of 2015 -- but he also helped Atlanta win six of its first seven and two of its last three, including a Week 16 matchup in which the Falcons ended the Panthers' dreams of an undefeated season. That said, I think the Panthers will win their fourth consecutive division title.

This is another division that made improvements from top to bottom, with three potential challengers to the Pats. The Bills did a lot to help themselves, extending left tackle Cordy Glenn and coming away with an impressive draft haul. Still, Brady or no, it's not wise to bet against Bill Belichick, who simply finds ways to win. I expect New England to ultimately capture its eighth consecutive division title.

3) Houston Texans

This division has really gotten better since its days as Andrew Luck's perennial punching bag. The Texans added a new quarterback (Brock Osweiler) and running back (Lamar Miller) and bolstered the receiver corps (Will Fuller and Braxton Miller) and O-line (center Nick Martin) in the draft. Coach Bill O'Brien is one of the better coaches in the NFL. But I simply like Jacksonville more, especially at the QB position.

2) Denver Broncos

Sure, the Broncos' monstrous defense made it possible for them to capture the Lombardi Trophy despite some less-than-inspiring quarterback play from Peyton Manning and Brock Osweiler (Denver led the NFL with 23 interceptions). And it's reasonable to expect likely starter Mark Sanchez to at least replicate the performance of Manning/Osweiler. But while Denver's D should again be good, it won't be as great as it was without Malik Jackson and Danny Trevathan, meaning it won't be able to counterbalance the deficiency under center as effectively. Thus, the door is open for a new division champion in 2016. Oakland will make some noise, but I like the Kansas City Chiefs to take the cake.

1) Cincinnati Bengals

This might be a bit of a surprise, since the Bengals won 12 games last year, including 10 of their first 12. And yes, they'll get quarterback Andy Dalton, who missed the last four games (including a wild-card lossto the Steelers) of the 2015 season due to a fractured thumb, back healthy. But they also lost quality receivers in Mohamed Sanu and Marvin Jones to free agency and -- perhaps even more importantly -- will have to replace former offensive coordinator Hue Jackson, now the Browns' head coach. Jackson was a very innovative and creative mind in Cincy, and he did a very good job. Thus, I expect this team to take a step back. But my pessimism regarding the Bengals' ability to hold on to the division has less to do with them and more to do with my confidence in Pittsburgh.

The bottom line is, the Steelers have a very imposing set of triplets in quarterback Ben Roethlisberger, running back Le'Veon Bell and receiver Antonio Brown. When all three are healthy, this is easily the best team in the division. Of course, injuries to Big Ben and Brown in 2015 and Bell in 2014 and 2015 are exactly what have stopped Pittsburgh. I cannot believe that the Steelers will be so unlucky as to be sabotaged by the injury bug for a third year in a row. And so I am confident we'll see a new AFC North champ in 2016.